What kind of repair? Is it leaking or does the slope need to be adjusted? Is your fascia in good condition still?
https://www.rona.ca/en/product/dap-b...E&gclsrc=aw.ds
If it’s a simple leak, you can get gutter seal and apply yourself.
If it’s major - use a pro.
Get a few quotes.
Links of knowledgeable contractors.
https://www.gutterdoctor.ca
https://shaamgutters.ca
https://westqualityroofingandexteriors.com